Diseases and Disorders
This unit covers
chapters 13, 14, 15, 20 and 21.
Infectious Disease
Chapter 13
Key Terms
 Non-infectious – A disease that cannot be
passed in the community.
 Infectious/Communicable – A disease that may
be passed around the community in a variety of
ways.
 Pathogen – Referring to the infectious agent that
causes disease.
Pathogens
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Bacteria – Microscopic, single celled organism. Multiplies asexually (cell division). There are millions of different bacteria
and most are harmless. Some are helpful (i.e. intestinal bacteria)
and some cause disease.
Virus – Smaller than bacteria, it is a DNA strand covered in
protein. Again, there are millions of viruses, but they can only
reproduce inside a cell that matches the virus. They do so by
taking over a specific cell and forcing it to reproduce the virus.
Fungi – A plant that lives off the nutrients of a living or dead
host. Athletes foot and jock itch are examples of fungal
infections.
Protozoan – Single celled microorganism that is larger and more
complex than bacteria. Malaria is an example of a disease caused
by a protozoan.
Parasites – Animals that live off a host. Lice and tapeworms are
examples.
How Infectious Disease Spreads
Person to Person - Direct contact through touching, kissing and
sex.
Airborne (some books lump this in with person to person) Sneezing and coughing spread pathogens through the air.
Contact with objects - Sharing of objects such as drinking glasses,
needles (tattoos and piercing), door and toilet handles.
Food and Water – Many diseases are spread through contaminated
food or drinks. (Jack-in-the-box, Mad Cow)
Animals and Insects – Examples are rabies spread by animal bites
and Malaria spread by mosquitoes.
Treatment
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Bacteria – Antibiotics are used to kill bacteria. It is important to
kill all the bacteria to avoid Antibiotic Resistance. Surviving
bacteria may be resistant to another round of the same antibiotic
treatment.
Virus – Your immune system must kill a viral infection. Most
anti-viral medications simply relieve the symptoms of the
disease.
Fungi – Fungicides are available OTC or by prescription.
Protozoan – Prevention is best through proper hygiene.
However, medical help is needed should an infection appear.
Parasitic - Again, prevention is best (don’t share combs, towels,
etc). Most parasitic infections, such as lice, can be cured with
OTC medications.
How Your Body Fights Disease
Physical Barriers
 Skin – Your skin keeps most pathogens from entering.
The enzymes in your sweat and body oils kill many
pathogens.
 Mucous Membranes – Mucous catches pathogens that
enter through your respiratory system and clears them
out by bringing the mucous to the back of your throat.
Swallowing will send the pathogens to the stomach.
 Chemical – Tears, sweat and stomach acid are all acidic
enough to kill most pathogens.
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Inflammation – When a pathogen (i.e. bacteria) breaks
through the barriers, the blood vessels around the
infection swell with blood and bring white blood cells
(Phagocytes) to the area. The white blood cells engulf
the invading substance, and deliver it to the lymph
nodes for destruction.
Immune System – The immune system is activated
when a virus is being reproduced in the body.
Here’s how it works.
Immune System
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A viral infection is discovered.
A Macrophage holds a virus and activates the helper T-cells
(T4). (You feel fine at this point.)
Helper T-cells activate B cells to start making antibodies and
killer T-cells. (You start feeling sick.)
Killer T-cells puncture the cells that are infected and the
antibodies enter to kill the virus. (You feel really sick.)
When all the viruses are dead, suppressor T-cells shut down
the process. (You will feel better soon.)
Memory T-cells and some B cells with antibodies are left on
patrol to kill any of the exact same kind of virus that may enter
later. This immunity is called Active Immunity.
Staying well
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Protect yourself – Maintaining a healthy body will boost your
immune system.
Eat healthy – poor diet choices weaken your immune system.
Drink water – Good hydration reduces illness.
Reduce Stress – Stress drains energy from the immune system.
Exercise – A strong cardiovascular system helps the immune
system.
Get regular check ups to gain early detection to serious diseases.
Avoid contact with sick people. Wash your hands often and
don’t share personal items.
Sleep – rest will boost immune function.
Get vaccinated – Vaccines are weakened or dead pathogens that
trigger the immune system without causing illness. You may feel
tired for a couple days, but that is better than being sick for
several days.
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Common Bacterial Illnesses
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Tetanus (severe muscle spasms) – Found in the dirt and
enters through cuts.
Strep Throat (sore throat, fever) – Spread by contact with
mucus from an infected person.
Sinus infection, ear infection
Meningitis (swelling of the membranes that cover the spinal
cord) – Spread through contact with saliva or mucous from
an infected person.
Salmonella (nausea, cramps, diarrhea) – Spread through
infected foods that were not cooked well enough.
Common Viral Diseases – Flu, Mumps, Cold, Measles,
Mononucleosis, and Hepatitis. All of these are spread
through contact with saliva, mucous or other body
fluids from an infected person. Your immune system
must kill the virus and you should never get the same
illness again.
So, why do we get colds and flu’s repeatedly? There are
thousands of different kinds of colds and flu’s and you
will need to develop antibodies to each one.
Other Common Infections
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Fungal – Athletes foot, Jock Itch, and Ringworm are most
common and can be spread through contact with objects or
person to person. Prevention through good hygiene is best.
Shower directly after athletics (at school), don’t share towels,
combs, clothes.
Protozoa – Malaria is the most serious disease and is spread
through insect bites from a diseased person to another person.
Amebic Dysentery is also common and spread through
contaminated water supplies.
Parasitic – Animals living on/in a host. Lice, leeches, ticks and
fleas are all examples of parasites that live on the skin. A
tapeworm is an example of a parasite that lives in the host.
Lifestyle Diseases, Ch. 14
Cardiovascular Disease – Damage to the
heart and blood vessels over years leads to
heart attack, stroke, atherosclerosis and
high blood pressure. This is the leading
cause of adult death in the USA.
Cancer – Uncontrolled cell growth in the form of
tumors. Malignant (cancerous) tumors invade
and destroy healthy cells. Causes of cancer vary,
but exposure to cancer causing agents
(carcinogens) certainly increase the risk.
Radiation, UV rays, chemicals in tobacco and
asbestos have all been proven to be carcinogens.
Some forms of cancer (i.e. breast) may be linked
more to genetics and early detection is the best
defense.
Diabetes – The pancreas is not producing
enough insulin ( a hormone) or the cells
don’t respond to the insulin. It takes an
interaction between the cells and insulin to
be able to use glucose for energy. If the
body is forced to use fats and protein all
the time, there is a build up of toxins in the
blood stream that can be toxic and result in
a diabetic coma.
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Type 1 Diabetes – The pancreas does not
produce insulin. The patient must usually inject
insulin several times each day.
Type 2 Diabetes – The cells do not respond to
the insulin. Although insulin injections may be
necessary, control is usually handled through
exercise and diet.
Why are these called “Lifestyle Diseases”?
Because they are caused partly by unhealthy
behaviors and partly by other factors.
Controllable risk factors:
-diet and body wt.
-activity level
-sun exposure
-smoking and alcohol abuse
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Uncontrollable risk factors:
Age
Gender
Ethnicity
Heredity
Ch. 15, Non-Infectious Diseases
Hereditary Disease – Abnormal chromosomes or
defective genes inherited from one or both
parents.
Gene – a segment of DNA located on a
chromosome that determines something about
you (i.e. hair color).
Single gene diseases – Sickle Cell Anemia (defective red
blood cells), Huntington’s disease (degeneration of
brain cells), Hemophilia (lack of blood clotting), Cystic
Fibrosis (mucous glands create thick mucous clogging
the lungs, pancreas and liver).
Complex Diseases – More than one gene defect leads to
being more prone to lifestyle diseases and type 2
diabetes.
Chromosomal Diseases – 23 pairs are normal. An
abnormal number causes problems (i.e. Down
Syndrome).
Immune Disorders
Autoimmune Diseases – The immune system mistakes
normal cells for foreign materials and attacks those
cells. Examples are, Rheumatoid Arthritis (joint
padding) and Multiple Sclerosis (insulation around
nerves in the brain).
Allergies – a reaction of the immune system to a harmless
substance. Reactions may be mild such as sneezing or
severe, such as difficulty breathing.
Asthma – Dust, smoke, exercise, foods and pollution can
cause the airways to narrow and clog with mucus.
Ch. 20, STDs
Sexually Transmitted Disease – Sexual contact is the usual
method of transmission.
STDs caused by bacteria – Chlamydia, Pelvic
Inflammatory Disease, Gonorrhea and Syphilis can all
be treated with antibiotics if caught early. Left
untreated they can cause scarring, sterility and pain.
The scarring can also cause ectopic pregnancy, where
the egg implants in the fallopian tube rather than the
uterus. Syphilis is the most dangerous because the
symptoms are a painless chancre sore that may not be
noticed. Up to six months later, a rash, fever and joint
pain along with hair loss. Two or more years later there
will be nerve/brain damage causing blindness, loss of
mental capacity and possible death.
STDs caused by virus – HPV (Genital Warts),
Genital Herpes, Hepatitis, HIV. There is no
cure.
STDs caused by parasites – Pubic Lice, Scabies
(mites that burrow into the skin),
Trichomoniasis (protozoan). These can be
treated with prescription medication.
Preventing STD’s
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Abstinence – Delay sexual relations until you are in a
monogamous relationship. This is the only 100%
method.
Monogamy – As long as both partners are
monogamous, there is no chance for infection.
Safer Sex – Latex condoms with water based lubricant.
70% effective. Condoms have an acceptable failure rate
and even under the best circumstances don’t provide
complete protection.
Don’t share needles.
Ch. 21, AIDS
HIV – Human Immunodeficiency Virus
AIDS – Acquired Immune Deficiency Syndrome. The set
of diseases that is eventually brought on by an HIV
infection.
Pandemic – HIV has spread quickly all over the world.
The fastest growing number in the U.S. is in people 15
to 24 years old.
Origins of HIV – Chimpanzee’s, hunted as a food source
in Africa, are the most likely to have been the source of
HIV in the human population. The virus does not
effect the chimp, so the chimp is a carrier.
How HIV works – The virus attacks the T-4 cells that
activate the immune system. The immune system will
start to fight the infection, but it is a losing battle.
Phase 1 – Asymptomatic stage in which no symptoms
appear. This may last up to ten years, but the person is
able to infect others.
Phase 2 – Swollen glands, fatigue, weight loss, fever,
diarrhea.
Phase 3 – AIDS. Opportunistic infections start which
include pneumocystis, tuberculosis (lungs),
toxoplasmosis (brain), Kaposi’s sarcoma (red, blotchy
skin cancer). One of these is likely to kill the patient.
Transmission of HIV
HIV is hard to get unless you participate in risky
behavior involving blood, semen or vaginal
fluid.
 Sexual activity – Oral, anal or vaginal sex.
Condoms are the only protection and they are
unreliable at best.
 Sharing needles – injections (heroin), tattoos,
piercing.
 Mother to child during birth or breast feeding.
This has been reduced to only a few cases per
year.
Testing for HIV
 Antibody test – Testing will only find antibodies,
not the virus itself.
 Retest – A false negative can happen for up to
six months. Antibodies need enough time to
grow in sufficient numbers to be found.